The subject matter disclosed herein relates generally to diagnostic imaging systems, and more particularly to Magnetic Resonance (MR) Radio-Frequency (RF) coils for diagnostic imaging systems.
Magnetic Resonance Imaging (MRI) systems and Nuclear Magnetic Resonance (NMR) imaging systems often include a superconducting magnet that generates a temporally constant (i.e., uniform and static) primary or main, magnetic field. MRI data acquisition is accomplished by exciting magnetic moments within the primary magnetic field using magnetic gradient coils. For example, in order to image a region of interest, the magnetic gradient coils are sequentially pulsed to create pulsed magnetic gradient fields in a bore of an MRI scanner to selectively excite a volume corresponding to the region of interest in order to acquire MR images of the region of interest. The resultant image that is generated shows the structure and function of the region of interest.
In these systems, RF coils, which may be transmit coils, receive coils or transmit and receive coils, are used to acquire the image information of the region of interest of a scanned object. For example, it is known to use a phased array configuration for RF coils in MRI, such as a surface phased array having multiple loop element coils, to receive NMR signals.
When using RF coils in multi-modality system, for example, when using MRI in combination with X-ray Computed Tomography (CT) or Positron Emission Tomography (PET), the RF coils can cause attenuation in the X-rays, transmitted by the CT system or the emissions received by the PET system. The attenuation of the signals can reduce the quality of images subsequently reconstructed. In order to overcome the attenuation, a higher X-ray or radiopharmaceutical dose may be used, which is undesirable, as it exposes the patient to higher levels of X-ray or radioactive isotopes that can be harmful. As a result, the MRI coils are often modified, such as to be more sparsely positioned, so that additional dose is not needed or reduced. However, this arrangement affects the overall system performance, for example, in the quality of images acquired.